The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it may be described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present technology.
Transmission components must be high strength and suitable for high torque capacities. Powder metal transmission components provide several technical benefits, and are becoming more attractive from manufacturing strategies and perspectives. Typical powder metal carrier structures may include three or more pieces in order to accommodate the various pinion gears and related components. The pieces may include a cylindrical shell or drum, one or more support member, a backing plate, and various other optional or auxiliary-type structures. Various powder metal transmission components may need to be aligned with one another for coordinated rotational movement. For example, an automatic transmission carrier may have a cover, and another part may neighbor the cover along the carrier's axis, but rotate about the axis at a different speed than the carrier. In this example, a wear resistant thrust washer may be placed on this axis, between the cover and the neighboring part. To retain the thrust washer, the thrust washer may be provided with claws, and the cover may be provided with complementary retention features. Prior attempts at face-forming such retention features have not been successful, and have led to failures during part ejection and/or to stressing of the tools. Thus, such retention features are commonly formed by machining holes or bores in the powder metal cover component after the sintering process.
Generally, reducing the need for machining of parts in any assembly reduces part production costs, and the time required for manufacturing. Accordingly, there remains a need for improved powder metal component retention features that provide strength and ease of manufacture, with the ability to meet the high torque requirements needed for use in a transmission.